chore(packages): Refactor package setups in within core

And get rid of:

- dash, doesn't need to be, packages which depend on it, should have it
  listed as a dependency
- smart-mode-line, don't need it anymore as I use the doom-modeline
  package to stylize the modeline.

core/siren-core-editor.el

@@ -66,7 +66,8 @@
 (global-auto-revert-mode t)
 
 ;; diminish keeps the modeline tidy
-(require 'diminish)
+(use-package diminish)
+
 (diminish 'visual-line-mode)
 
 ;; Enable mouse support when running in a console

core/siren-core-env.el

@@ -7,9 +7,10 @@
 
 ;;; Code:
 
-(require 'exec-path-from-shell)
-(when (memq window-system '(mac ns x))
-  (exec-path-from-shell-initialize))
+(use-package exec-path-from-shell
+  :config
+  (when (memq window-system '(mac ns x))
+    (exec-path-from-shell-initialize)))
 
 (provide 'siren-core-env)
 ;;; siren-core-env.el ends here

core/siren-core-packages.el

@@ -35,10 +35,6 @@
                 (not (y-or-n-p (format "Delete repository %S?" repo))))
       (delete-directory (straight--repos-dir repo) 'recursive 'trash))))
 
-(straight-use-package 'dash)
-(straight-use-package 'diminish)
-(straight-use-package 'exec-path-from-shell)
-(straight-use-package 'smart-mode-line)
 (straight-use-package 'use-package)
 
 (provide 'siren-core-packages)

core/siren-core-ui.el

@@ -48,11 +48,5 @@
                               (abbreviate-file-name (buffer-file-name))
                             "%b"))))
 
-(require 'smart-mode-line)
-(setq sml/no-confirm-load-theme t)
-;; delegate theming to the currently active theme
-(setq sml/theme nil)
-(add-hook 'after-init-hook #'sml/setup)
-
 (provide 'siren-core-ui)
 ;;; siren-core-ui.el ends here